Problem: $ { {0} \times \left[\begin{array}{r}{2} \\ {-1} \\ {3}\end{array}\right] = {?} } $
Solution: To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{r}{0}\times{2} \\ {0}\times{-1} \\ {0}\times{3}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{r}{0} \\ {0} \\ {0}\end{array}\right]}$